Right Array Division : Ignoring division by zeroes

Question

I have two data matrices A and B of similar dimensions. I intend to divide each element of A by its corresponding elements of B. For this matlab provides a shortcut as C = A./B. However, B has many zero elements , for such elements I want elements of C to be zero rather than NAN . Does MATLAB provide a way to do this in an efficent manner? I could do this in a loop but that would be very expensive. Thanks.

Answer 1

Yes. You can use logical indexing:

C = zeros(size(A));
t = logical(B);
C(t) = A(t)./B(t);

With logical indexing, only the elements of A, B and C corresponding to true elements of t will be evaluated. t is true only where B is non-zero. Note that C is pre-initialized to zeros to automatically take care of the cases that are not evaluated because B is zero.